The present invention relates generally to agricultural machinery and, more particularly to improvements in separators for combine harvesters for agricultural crops.
The invention concerns a combine harvester with a cutting bar and a sloping conveyor, which transports the cut material away. A tangential or axial thresher is mounted behind the sloping conveyer, which is followed in the direction of flow of material by at least one separating device. The separating device works by the axial-flow method and comprises at least one drivable separating rotor which is rotationally surrounded by a housing. Over a certain conveying distance, the drivable separating rotor is constructed as a chopping device for the straw and cooperates with chopping blades. The cylindrical main body of the separating rotor carries several rows of impact teeth which extend in the longitudinal direction, preferably helically or arcuately, and which are arranged on supporting rings spaced apart from one another.
The combine harvester in question is particularly suitable for harvesting cereal grain. After threshing out the grain with the thresher it is necessary to separate out the grain from the grain and straw mixture. The separating device here, which works by the axial-flow method, ensures continuous transport of the straw around the separating rotor. This is achieved by the helically or spirally extending conveying elements, such as conveying strips for example, in cooperation with guide webs in the rotor housing. The guide webs can run parallel to and at a distance from the axis of rotation of the separating rotor or likewise be arranged helically or spirally. Usually the separating rotor is equipped with four conveying elements which are each respectively offset from one another by an angle of 90 degrees and arranged in rows. The outer edges of the conveying elements, which are constructed as conveying strips and whose edges face away from the axis of rotation are sawtooth-shaped. Most combine harvesters are equipped with a chopping device for the straw which can be used selectively, depending on whether the straw is to be deposited in swathes or is to be distributed as chopped material over the harvested field surface. The separating rotor of the separating device, which works by the axial-flow method, can work opposite the direction of forward travel of the combine harvester or transversely thereto. In the former case, the axis of rotation of the separating rotor is transverse and in the latter case the axis of rotation is parallel and at a distance from the wheel axles of the combine harvester.
A combine harvester in European patent publication 0 748 583 A1, shows a main body of the separating rotor in the region of the chopping device which has a smooth surface. In order to chop the straw, it is equipped with a plurality of supporting rings which are spaced apart from each other. These supporting rings carry the impact teeth on the circumferential side. It can be seen from this patent that the supporting rings are fixed to the main body of the separating rotor by a welded connection or screw connection. Such connecting techniques known in the art however cause the assembly time to be extremely long. As the impact teeth are regarded as wearing parts, after an operating time which cannot be determined exactly, it becomes necessary to exchange the supporting rings with the impact teeth. The time for dismantling and for subsequent assembly is extremely long. Moreover, the possibility of the impact teeth being damaged, for example by foreign bodies, exists. Thus, either all the supporting rings or only some may have to be exchanged. Thus, the prior-art construction is not particularly maintenance and assembly-friendly and, due to the long assembly times, can be relatively cost-intensive.
German patent publication 197 20 074 A1 proposes that the impact teeth of one row form a single-piece impact tooth functional part which is releasably attached to the main body of the separating rotor. Filler bodies, which are provided with cutting grooves for the chopping blades, are arranged between the rows of impact teeth. The filler bodies located between two rows of impact teeth are constructed in one part and also releasably attached to the main body of the separating rotor or to an adjoining impact tooth functional part. German patent 197 20 074 A1 also presents a solution in which each impact tooth functional part and the filler body behind it in the direction of rotation are also in one part. However, this solution also requires significant assembly time, so that this proposed solution also cannot be structurally converted.
It is an object of the present invention to overcome one or more of the above-described difficulties.
Another object is to provide a combine harvester having a separator which is structurally simple, thus significantly simplifying the assembly of the supporting rings of the chopping device.